title: Active sites of beta-lactamases. The chromosomal beta-lactamases of Pseudomonas aeruginosa and Escherichia coli.
abstract: An acyl-enzyme was isolated from certain chromosomal beta-lactamases and a penicillin. The penicillin was cloxacillin which, although it is a substrate for these enzymes, has such a low kcat. that it functions as an inhibitor. The enzymes were from the mutant of Pseudomonas aeruginosa 18 S that produces the beta-lactamase constitutively [Flett, Curtis & Richmond (1976) J. Bacteriol. 127, 1585-1586; Berks, Redhead & Abraham (1982) J. Gen. Microbiol., in the press] and from Escherichia coli K-12 (the ampC beta-lactamase) [Boman, Nordström & Normak (1974) Ann. N.Y. Acad. Sci. 235, 569-586]. The acyl-enzymes have been degraded to determine the residue labelled, and the sequence around it. The residue labelled is serine. The sequences around the labelled serine in these two beta-lactamases are exceedingly similar. However, the sequences are quite different from those around the active site serine in the beta-lactamases previously studied. There is thus more than one class of serine beta-lactamases.
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D002876:Chromosomes, Bacterial / Q000201:enzymology*; D003023:Cloxacillin / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D010446:Peptide Fragments / Q000302:isolation & purification; D011550:Pseudomonas aeruginosa / Q000201:enzymology*; D001618:beta-Lactamases / Q000145:classification / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D001618:beta-Lactamases; D003023:Cloxacillin